Kis Loránd L, Nishikawa Jun, Takahara Miki, Nagy Noémi, Matskova Liudmila, Takada Kenzo, Elmberger P Göran, Ohlsson Ann, Klein George, Klein Eva
Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden.
Int J Cancer. 2005 Mar 1;113(6):937-45. doi: 10.1002/ijc.20654.
In about 50% of classical Hodgkin lymphomas, the Hodgkin/Reed Sternberg (H/RS) cells carry Epstein-Barr virus (EBV). The viral gene expression in these cells is restricted to EBNA-1, EBERs, LMP-1 and LMP-2 (type II latency). The origin of H/RS cells was defined as crippled germinal center B cells that escaped apoptosis. In spite of numerous attempts, only few typical Hodgkin lymphoma (HL) lines have been established. This suggests that the cells require survival factors that they receive in the in vivo microenvironment. If EBV is expected to drive the cells for growth in culture, the absence of EBNA-2 may explain the incapacity of H/RS cells for in vitro proliferation. In EBV carrying B lymphocytes, functional EBNA-2 and LMP-1 proteins are required for in vitro growth. For analysis of the interaction between EBV and the H/RS cells, we infected the CD21-positive HL line KMH2 with the B958 and Akata viral strains. Only EBNA-1 expression was detected in a few cells in spite of the fact that all cells could be infected. Using a neomycin-resistance-tagged recombinant EBV strain (Akata-Neo) we established an EBV-positive subline that was carried on selective medium. In contrast to the type II EBV expression pattern of H/RS cells in vivo, the KMH2 EBV cells did not express LMP-1. The EBV expression pattern could be modified in this type I subline. LMP-1 could be induced by the histone deacetylase inhibitors TSA and n-butyrate, by 5-AzaC, a demethylating agent, and by phorbol ester. None of these treatments induced EBNA-2. Importantly, exposure to CD40 ligand and IL-4 induced LMP-1 without EBNA-2 expression and lytic replication. The KMH2 EBV cells expressed LMP-2A, but not LMP-2B mRNAs. This result is highly relevant for the type II expression pattern of H/RS cells in vivo, since these stimuli can be provided by the surrounding activated T lymphocytes.
在大约50%的经典型霍奇金淋巴瘤中，霍奇金/里德·斯腾伯格（H/RS）细胞携带爱泼斯坦-巴尔病毒（EBV）。这些细胞中的病毒基因表达仅限于EBNA-1、EBERs、LMP-1和LMP-2（II型潜伏）。H/RS细胞的起源被定义为逃避凋亡的有缺陷生发中心B细胞。尽管进行了大量尝试，但仅建立了少数典型霍奇金淋巴瘤（HL）细胞系。这表明这些细胞需要在体内微环境中获得的生存因子。如果预计EBV会驱动细胞在培养中生长，EBNA-2的缺失可能解释了H/RS细胞无法在体外增殖的原因。在携带EBV的B淋巴细胞中，功能性EBNA-2和LMP-1蛋白是体外生长所必需的。为了分析EBV与H/RS细胞之间的相互作用，我们用B958和Akata病毒株感染了CD21阳性的HL细胞系KMH2。尽管所有细胞都能被感染，但仅在少数细胞中检测到EBNA-1表达。使用带有新霉素抗性标签的重组EBV株（Akata-Neo），我们建立了一个在选择性培养基上维持的EBV阳性亚系。与体内H/RS细胞的II型EBV表达模式不同，KMH2 EBV细胞不表达LMP-1。在这个I型亚系中，EBV表达模式可以被改变。组蛋白去乙酰化酶抑制剂TSA和丁酸钠、去甲基化剂5-氮杂胞苷以及佛波酯均可诱导LMP-1表达。这些处理均未诱导EBNA-2表达。重要的是，暴露于CD40配体和IL-4可诱导LMP-1表达而无EBNA-2表达及裂解复制。KMH2 EBV细胞表达LMP-2A mRNA，但不表达LMP-2B mRNA。这一结果与体内H/RS细胞的II型表达模式高度相关，因为这些刺激可由周围活化的T淋巴细胞提供。
